This invention relates to a system for inerting a casting vessel, such as a traversable ladle or torpedo vessel, used for transporting molten metal, the vessel being used when tapping a blast furnace. With the vessel positioned below the molten metal outlet opening at a transfer station, the vessel cavity is flushed with an inert gas both above the cavity inlet and during inflow of the molten metal into the vessel, in such a manner that contact between the molten metal surface in the vessel and the atmosphere is effectively prevented.
A related system of this type is disclosed in German Patent No. 39 03 444 in which inert gas is forced into the interior of the casting vessel through a flexible feed line in the vicinity of the vessel while positioned below the molten metal outlet opening at a transfer station. A disengageable coupling is attached to the casting vessel, and a stationary pipe is connected to that coupling on the outer surface of the vessel having a through opening in the wall thereof. Such openings are arranged to lie above the maximum molten metal level in the vessel and below the inlet opening of the casting vessel at its upper edge.
The drawback of such arrangement is that all casting vessels used for transporting molten metal in a metallurgical operation must be provided with an inlet opening or openings in the vessel wall thereof, such that special consideration must be taken with a realization that such openings must penetrate both the outer metal jacket and the conventional refractory lining of the casting vessel And, such openings are unusually made after the vessel finishing operation which is time consuming and uneconomical.
And, when a casting vessel is relined due to wear such openings which again need be made involve additional time-consuming treating operations.
Despite the care taken in the provision of such openings it is difficult to assure that the molten metal or slag will not flow into such openings and plug them despite the specified distance between the molten liquid level and the open end of the vessel. The plugging occurs while filling the vessel with molten metal and only leads to expensive maintenance work.
Moreover, the prior art system requires the coupling and uncoupling of the flexible inert gas feed line to or from the stationary pipe on the vessel which demands additional operations and care, normally carried out manually, can involve a complex operation especially when the casting vessel is Positioned below a casting platform since pressurization of the feed line with inert gas is controlled normally on or below the casting platform. Improper coupling and uncoupling and improper inert gas feed control can lead to serious damage to the entire system and to the undesired outflow of inert gas.
The aforementioned drawbacks result in added costs due to increased investment and maintenance, and results in added safety risks.